In a statement to Entertainment Weekly, HBO confirms that it was the target of a hack, though the company doesn’t appear to be quite sure what the damage is yet.

So far, episodes of the HBO series Room 104 and Ballers have trickled out online. Though new episodes of its bloody centerpiece Game of Thrones have yet to surface, the leak reportedly contains writing suspected to be either a treatment or a script of an upcoming Game of Thrones episode, which is a big deal in its own right. HBO notified its employees of the breach Monday morning and hackers claim to have made off with 1.5 terabytes of HBO data, alluding that more leaks are on the way.

“As most of you have probably heard by now, there has been a cyber incident directed at the company which has resulted in some stolen proprietary information, including some of our programming,” HBO CEO Richard Plepler wrote in an email published by Entertainment Weekly. “Any intrusion of this nature is obviously disruptive, unsettling, and disturbing for all of us. I can assure you that senior leadership and our extraordinary technology team, along with outside experts, are working round the clock to protect our collective interests.”

Following the major Sony hack back in 2014, entertainment companies remain jittery about this sort of thing. Still, given the scale of production, level of secrecy and vast room for human error surrounding new film and TV releases, it’s a wonder that anything manages to premiere without first popping up online.